Arrangement and mounting of the enclosure and combustion chamber of a forced-draft boiler

ABSTRACT

In the forced-draft boiler construction disclosed herein, a Ushaped partition, together with the upper portion of an overall enclosure, forms an air-tight compartment. A burner rests in the lower portion of the U-shaped partition while a heat-exchanger bridges the upper portion of the U-shaped partition. The heat exchanger includes a skirt which extends down into the lower portion of the partition, the forced-draft air flow causing inlet air to pass between the partition and the skirt.

United States Patent Calvin et al.

[ Nov. 25, 1975 ARRANGEMENT AND MOUNTING OF THE ENCLOSURE AND COMBUSTION CHAMBER OF A FORCED-DRAFT BOILER Inventors: Guy Edmond Calvin, Saint Maur;

Andre Marcel Costecalde, Fontenay-sous-Bois,, France Assignee: Saunier Duval, Rueil Malmaison,

France Filed: Dec. 12, 1974 Appl. No.: 531,888

Foreign Application Priority Data Dec. 13, 1973 France 73.44462 US. Cl 122/262; l22/DIG. 1; 122/367 C; 126/85 B Int. Cl. F22B 15/00; F28F 1/24 Field of Search l22/DIG. 1, 250 R, 367 R, 122/367 C, 262; 431/157; 126/85 B References Cited UNITED STATES PATENTS 1/1968 Keppel et a1 431/157 X 3,388,692 6/1968 Hale 122/367 3,707,142 12/1972 Kobayashi. 3,797,477 3/1974 Ramey 3,800,748 4/1974 Schindler et a1. 126/85 X Primary Examiner1(enneth W. Sprague Attorney, Agent, or FirmKenway & Jenney [57] ABSTRACT In the forced-draft boiler construction disclosed herein, a U-shaped partition, together with the upper portion of an overall enclosure, forms an air-tight compartment. A burner rests in the lower portion of the U-shaped partition while a heat-exchanger bridges the upper portion of the U-shaped partition. The heat exchanger includes a skirt which extends down into the lower portion of the partition, the forced-draft air flow causing inlet air to pass between the partition and the skirt.

6 Claims, 2 Drawing Figures US. Patent Nov. 25, 1975 SheetlofZ 3,921,592

Sheet 2 of 2 US. Patent Nov. 25, 1975 FIG.

ARRANGEMENT AND MOUNTING OF THE ENCLOSURE AND COMBUSTION CHAMBER OF A FORCED-DRAFT BOILER BACKGROUND OF THE INVENTION The invention concerns an air-tight forced-draft boiler and relates more precisely to a new arrangement of the enclosure provided for the fresh air intake and flue gas exhaust.

Water-heaters or gas boilers are already known whose combustion chambers are connected to the atmosphere outside the room. These systesm are, in some cases, surrounded with an intermediate chamber for an air feed which envelops the combustion chamber in an air-tight manner. In other more recent known systems, the outer jacket of the system forms this air-tight intermediate chamber and it is through an orifice arranged in the back wall of said jacket that the fresh air is admitted, which air circulates in said chamber before passing to the burners in the combustion chamber, the flue gasses being exhausted from this combustion chamber by means of a hood, an exhaust fan, and an outlet tube. The outlet tube is known to be advantageously concentric with the fresh air inlet tube.

Systems of this type, however, have a number of problems especially with regard to their mounting, their accessibility, and their tightness. One aspect appears particularly difficult because of the need to use a transverse and substantially horizontal wall located at the lower part of the system between the gas and water opening and regulating mechanisms on the one side and the burner on the other. This transverse wall must be connected tightly in particular with the back wall and the front wall of the system; tightness must also be ensured at the points where the gas or water tubes pass through, which creates a number of problems in mounting and accessibility.

SUMMARY OF THE INVENTION The purpose of the invention is to remedy the abovecited difficulties inherent in known systems and hence proposes a particular arrangement of the tight enclosure characterized by the fact that a U-shaped partition composed of two vertical walls extended at the top by horizontal shoulders and a transverse bottom is applied to the sheet-metal which forms the back wall of the system thereby to provide, at the base of the air-tight enclosure, a chamber of smaller width than the upper part of said enclosure; it is also characterized by the fact that the horizontal shoulders which are provided at the upper part of the partition and are attached to the lateral walls of the system are traversed by the tubes feeding in the water and bringing it to the heating element. Preferably, a front wall, shaped like two superimposed rectangles, is provided in which the lower rectangle has a smaller width and conforms closely to the lateral borders of the partition.

According to another characteristic of the invention, the heating element is provided with a skirt in the form of a rectangular case which fits within the U-shaped partition with sufficient clearance for fresh air to pass between the skirt and the housing.

According to a preferred embodiment of the invention, the transverse bottom of the housing is provided with a recess permitting introduction of an element supporting the burner which also serves as a passage for the tubes feeding gas to the burner and the pilot as well as the ignition and safety elements.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is an exploded perspective view of the entire system; and

FIG. 2 is a schematic front view, where the wall has been removed.

Corresponding reference characters indicate corresponding parts throughout the several views of the drawings.

DESCRIPTION OF THE PREFERRED EMBODIMENT The boiler enclosure shown comprises a back wall 5 provided with supports 2 for its attachment to the wall of the room whereon it is mounted, two lateral walls 3, whose upper parts are made of continuous sheet metal but whose lower parts have wide openings, and an upper lid 4. These four elements are welded together. A U-shaped partition I, obtained by stamping, is formed with a transverse bottom 10 and two vertical walls 11 ending in horizontal shoulders 12, the bent-up ends of which permit the housing to be mounted on lateral walls 3. The partition 1 is thus mounted inside the enclosure such that the horizontal shoulders 12 are substantially at the level of the top of the openings provided in lateral walls 3. Partition 1, which forms the bottom limit of the volume of the air-tight enclosure, also has lengthwise a small border or flange of folded sheet metal 14 and the transverse bottom is supplied toward the front with a V-shaped recess 15. The base of the air-tight enclosure so made is thus a chamber whose width is smaller (limited by vertical walls 11) than the upper part whose width is limited by lateral walls 3.

A burner element 6, together with a pilot tube 7 and an ignition and safety device 8, is attached to a support 16, also V-shaped, so as to be easily placed in the bottom part of the enclosure, in the small width chamber, since said support 16 fits into recess 15 of transverse bottom 10. Air-tightness is ensured by a rubber gasket (not shown) which borders said support 16. The gasket provides a sealed passage for the tubes feeding gas to the pilot and burner, for the usual high-voltage ignition wire of the pilot and for the connection of the usual flame control thermocouple.

A heat exchange element 9, of conventional construction, bridges the U-shaped partition, supported by its water tubes 20 which, provided with collars 21, rest on the horizontal shoulders 12 of the partition. For this purpose, shoulders 12 are supplied with apertures for passage of these principal pipes and with auxiliary apertures for passage of temperature sensors or overheating detectors if desired. All these apertures are sealed by appropriate sealing devices. These tubes, which thus pass outside vertical walls'll of the housing, are easily accessible through the apertures in the lateral walls and can thus be connected to the mechanisms (not shown) conveniently located in the lower part of the system under bottom 10 of the housing. I

The heat-exchange element 9 is provided with a rectangular skirt comprising a removable front plate 22 and a corrugated sheet metal assembly 23 forming the back plate and two lateral plates. The heat-exchange element is also provided with tabs 24 which bear on brackets mounted on the horizontal shoulders 12. The lower part of the skirt covers burning element 6. The inside of this skirt is supplied with a refractory lining for heat insulation thereof. It is kept apart from back wall 5 and vertical walls 11 of the housing by bosses (not represented) made when the walls are stamped.

The flue gas exhaust hood 25 rests on the upper part of heat exchange 9. It has the shape of a prism, one side of which is supplied with an aperture 26. On this aperture is mounted exhaust fan 29 whose outlet tube 30 passes concentrically through the larger diameter of air inlet orifice 31 provided in the back wall 5 of the system. Said orifice 31 also cooperates with a fresh air inlet tube 32 which connects the air-tight enclosure with the outside of the room.

Finally, a front wall 33 whose shape is as shown, i.e. with the upper part having the width of the overall enclosure and the lower part that of the lower part of the partition 1, is applied to the air-tight portion of the enclosure so formed. A window 34 enables pilot? to be seen while bosses 35, obtained by stamping, keep removable front plate 22 at a certain distance from this front wall.

The entire lower part of the overall enclosure, under partition 1, serves to enclose the pump and the control mechanisms (not shown). An easily dismountable outside facing covers the assembly.

FIG. 2 illustrates the air and flue gas paths in the system more clearly. It should be understood that front wall 33 does not appear on this drawing: it is known to be applied tightly to the edges of the enclosure limited by lid 4, lateral walls 3, and partition 1, the contours of which it matches exactly. Air and gas movement inside the enclosure is accomplished in a manner known of itself by fan 29. The fresh air is admitted from the outside by aperture 31. It circulates in the direction indicated by the arrows to the base of the enclosure whereby it passes between the partition 1 and the skirt of the heat-exchange element, whereby the restricted space, delimited by the spacing bosses, causesmore rapid air flow which facilitates heat exchange. The air passes under burner 6 and the flue gases collect in hood 25 and are exhausted by fan 29 through exhaust pipe 30. In order that said flue gases may not or may only slightly flow into the enclosure wherein fresh air is circulating, it will be noted that, by its design, the hood extends slightly beyond the upper part of the heating element and skirt (22, 23) and also covers the lower part of the heating element. Finally, FIG. 2 shows a surge tank 36 which is placed behind the system between back 5 and the wall of the room on which the system is mounted.

The system thus described as a non-limitative example is of small size, the inside enclosure having a volume well filled by the burning assembly and the heating element. As soon as front wall 33 is removed, the burner can easily be dismounted after removable plate 22 of the skirt has been lifted out, its support 16 being disengaged from recess 15. The hood itself is easily placed on heating element 9. The latter can also be raised such that tubes can be removed from the orifices provided in the horizontal ledge.

Mounting and dismounting are thus extremely simple for a system of this type. i

In addition, the fact that front wall 33 covers only the tight enclosure leaves all the mechanisms located in the lower part fully accessible: during normal operation they are concealed only by an easily removable external facing, even a pivoting or tilting facing. These mechanisms are also properly ventilated by the ambient air. Since they are heat insulated from the hot part by partition 1, they can be made of normal material,

particularly with plastic pieces.

In view of the foregoing, it may be seen that several objects of the present invention are achieved and other advantageous results have been attained.

As various changes could be made in the above constructions without departing from the scope of the invention, it should be understood that all matter contained in the above description or shown in the accompanying drawings shall be interpreted as illustrative and not in a limiting sense.

What is claimed is:

1. A forced-draft furnace comprising:

a rectangular enclosure, thhe top portion of which is substantially imperforate except for a combustion air inlet and a combustion products outlet in' the back panel of said enclosure; a U-shaped partition separating top and bottom portions of said enclosure;

resting in the lower portion of said partition; a

burner;

a heat exchanger bridging said U-shaped partition,

said heat exchanger being provided with a shroud, including a skirt portion which extends down into the depending portion of said partition with a predetermined gap therebetween; and means for exhausting combustion products from said shroud through said outlet, whereby air entering said inlet passes around said shroud and through said gap between said skirt and the depending portion of said partition to said burner. 2. A furnace as set forth in claim 1 wherein the top.

, part of said enclosure and the lower portion of said partition form an air-tight compartment in the shape of sua rectangular enclosure, the top portion of which is substantially imperforate except for a combustion air inlet and a concentric combustion productsoutlet in the back panel of said enclosure; bridging said enclosure, a U-shaped partition having laterally-extending horizontal shoulders, said partition separating top and bottom portions of said en- 7 closure; mounted in the lower portion of said partition, a

burner; a water-tube heat exchanger bridging said said heat exchanger being provided with a shroud including a skirt portion which extends down into 4 I the depending portion of said partition with a pre determined gap therebetwen; and

means including a blower for exhausting combustion products from said shroud through said outlet, whereby air entering said inlet passes around said shroud and through said gap between said skirtand I the depending portion of said partition to said ing the spacing of said skirt therefrom.

1 wherein said out- U-shaped partition, said heat exchanger having inlet and out let tubes which turn downwardly fromthe sides of said exchanger and extend through said shoulders, 

1. A forced-draft furnace comprising: a rectangular enclosure, thhe top portion of which is substantially imperforate except for a combustion air inlet and a combustion products outlet in the back panel of said enclosure; a U-shaped partition separating top and bottom portions of said enclosure; resting in the lower portion of said partition, a burner; a heat exchanger bridging said U-shaped partition, said heat exchanger being provided with a shroud including a skirt portion which extends down into the depending portion of said partition with a predetermined gap therebetween; and means for exhausting combustion products from said shroud through said outlet, whereby air entering said inlet passes around said shroud and through said gap between said skirt and the depending portion of said partition to said burner.
 2. A furnace as set forth in claim 1 wherein the top part of said enclosure and the lower portion of said partition form an air-tight compartment in the shape of superimposed rectangles, there being a front cover matching the contour of the compartment.
 3. A furnace as set forth in claim 1 wherein said heat exchanger is of the water tube type.
 4. A furnace as set forth in claim 1 wherein said outlet is concentric within said inlet.
 5. A forced-draft boiler comprising: a rectangular enclosure, the top portion of which is substantially imperforate except for a combustion air inlet and a concentric combustion products outlet in the back panel of said enclosure; bridging said enclosure, a U-shaped partition having laterally-extending horizontal shoulders, said partition separating top and bottom portions of said enclosure; mounted in the lower portion of said partition, a burner; a water-tube heat exchanger bridging said U-shaped partition, said heat exchanger having inlet and outlet tubes which turn downwardly from the sides of said exchanger and extend through said shoulders, said heat exchanger being provided with a shroud including a skirt portion which extends down into the depending portion of said partition with a predetermined gap therebetwen; and means including a blower for exhausting combustion products from said shroud through said outlet, whereby air entering said inlet passes around said shroud and through said gap between said skirt and the depending portion of said partition to said burner.
 6. A boiler as set forth in claim 5 wherein said partition and said enclosure walls have bosses for maintaining the spacing of said skirt therefrom. 